A "rocket-assisted" airplane takes off sooner than a plane without rockets. Both planes started at the same position and time.+ Full image and caption

The first substantial influx of money came from the United States Army Air Corps. The U.S. had not yet entered World War II, but the military wanted small rockets that could lift heavy aircraft off the ground. In August 1941, Frank Malina - one of the original "rocket boys" - headed a group that equipped an Ercoupe plane with rockets. The modified Ercoupe lifted off in half the normal distance. This method was named "Jet Assisted Take-Off," and the rockets were called JATOs.

After the successful development of this rocket, and the United States' entry into World War II, the Army asked for other types of rockets. In 1944, JPL began to develop guided missiles. These differed from JPL's earlier rockets because they would have guidance systems to steer them toward their targets.

JPL's first completely successful test was achieved with the WAC Corporal, launched Oct. 11, 1945. The rocket reached an altitude of 70 kilometers (almost 44 miles), a record at the time. The Corporal missile system JPL developed for the Army used liquid fuels. Launching a Corporal was quite an event. The fuel, the missiles, the launch equipment and the guidance equipment had to be transported separately. This made for convoys with dozens of trucks. The launch itself took lots of people and many hours of preparation.

JPL simplified its last missile for the Army and called it the Sergeant. Sergeant used a solid fuel that was part of the missile, reducing the number of people and amount of time necessary to launch it. The earliest Sergeant tests were carried out at White Sands, New Mexico, in January 1956. In 1959, however, the Army transferred the project to an industrial contractor, the Sperry Corporation, with JPL maintaining a consulting role for many years.